Time trends in caesarean section rates and associations with perinatal and neonatal health: a population-based cohort study of 1 153 789 births in Norway.

Objectives: To study caesarean section (CS) rates and associations with perinatal and neonatal health in Norway during 1999-2018.

Design: Population-based cohort study.

Setting: Medical Birth Registry of Norway.

Participants: 1 153 789 births and 1 174 066 newborns.

Methods: CS, intrapartum, perinatal and neonatal mortality rates expressed as percentages (%) or per mille (‰) with 95% CIs.

Primary And Secondary Outcome Measures: CS rates in the Robson Ten-Group Classification System; intrapartum, perinatal and neonatal mortality rates.

Results: The overall CS rate increased from 12.9% in 1999 to 16.7% in 2008 (p<0.001), and then reduced to 15.8% in 2018 (p<0.001). The largest reductions were observed in Robson groups 2 and 4. In Robson group 2, the planned CS rate decreased from 9.6% in 2007-2008 to 4.6% in 2017-2018, the intrapartum CS rate decreased from 26.6% in 2007-2008 to 22.3% in 2017-2018. In Robson group 4, the planned CS rate decreased from 16.1% in 2007-2008 to 7.6% in 2017-2018, and the intrapartum CS rate decreased from 7.8% in 2007-2008 to 5.2% in 2017-2018.The intrapartum fetal mortality rate decreased from 0.51 per 1000 (‰) in 1999-2000 to 0.14‰ in 2017-2018. Neonatal mortality decreased from 2.52‰ to 1.58‰.

Conclusions: CS rates in Norway increased between 1999 and 2008, followed by a significant reduction between 2008 and 2018. At the same time, fetal and neonatal mortality rates decreased. Norwegian obstetricians and midwives have contributed to maintaining a low CS rate under 17%. These findings indicate that restricting the use of CS is a safe option for perinatal health.